Manufacture of metallic filaments for incandescent electric lamps.



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' HARRY BRESLER, CHARLOTTENBURG, GERMANY, ASSIGNOR, BY MESNE-ASS IGN- MENTS, TO GENERAL ELECTRIC G(Y'IHCEIIEAN'Y, A CORPORATION OF NEW YORK.

subject of the Emperor of MANUFACTUREOF METALLIC FILAMENTS'FOR INCANDESCE-NT ELECTRIC LAMPS.

No Drawing.

To all whom it may concern:

Be it known that I, HARRY Bnnsunn, 2. Germany, and resident of Oharlottenburg, Germany, have invented certain new and useful Improvements in the'Manufactur of Metallic Filaments for Incandescent Electric Lamps, of which the following is a specification.

My invention relates to the manufacture of metallic filaments for incandescent electric lamps, and particularly to the production of a plastic paste or mass from which such filaments may be formed by the wellknown squirting process or in any' other approved manner.

In carrying out my present invention, I take a fine powder of a suitable metal, such as tungsten ormolybdenum, either alone or mixed with oxide of such metal, and by the addition of a small amount of binder consisting of a solution of ammonium viscose, I produce a lastic mass or paste. This mass is then ormed by squirting or otherwise into filaments which: are subsequently converted into metallic filaments by a suit able treatment, as by drying the filament in the open air and heating it in an atmosphere of hydrogen. This results in a carbonization of the filament, or rather of the binder it contains. This binder is decomposed by the heat, the ammonium sulfid escaping as a gas and the cellulose being burned or carbonized. This carbonizing step may be carried out in a porcelain tube heatedexternally by Bunsen burners, the air originally contained in such tube being driven out by a current of hydrogen passed therethrough. The quantity of carbon resulting from this treatment should be exactly or approximately suflicient to combine with the oxygen of the oxid, and the pro- Specification of Letters Patent.

Application filed January 9, 1909. Serial No. 471,533.

Patented Apr. 16, 1912'.

ment, but if there is any excess, it should be of oxid. Any remnant of oxid not decomposed by the. carbon, will be reduced by the action of the hydrogen current, so that 'a pure metallic filament is obtained. In order to give these filaments good electrical conductivity, they are then brought to red heat by an electric current either in a vacuum or in an atmosphere of nitrogen.

Among the advantages of the viscose binder are the smallness of the carbon residueleft by it, the small amount of it that sufiices for efficient binding action,the advantage of these two properties being of course, cumulative,and the relatively low temperature at which it decomposes. Besides-the lowcarbon content, efiicient binding action, and low temperature of decomposition characteristic of viscose itself, the ammonium solution has the advantage that the solvent leaves no residue of any sort.

I claim as 'my invention:

1. A squirting mixture for the formation of filaments comprising material held-in .a

binder of ammonium viscose.

2. A plastic paste for filament manufacture comprising finely divided tungsten held in a binder of ammonium viscose.-

3. A plastic mixture for the production of filaments comprising finely divided material held in a solution of viscose.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses. HARRY BRESLER.

Witnesses:

JOHN Lorna, JOHN A. KEHLENBECK. 

